Since many gene products such as RNA and proteins are enriched in regions where they function, their location provides an important clue to their function. This property has been used for in situ fluorescent hybridization, immunohistochemistry and tissue-specific reporter assays in numerous areas of biological research.
Current methods involve extracting nucleic acid molecules from their native environment or making synthetic nucleic acid molecules, amplifying them in solution and placing them on a flat array surface or beads for gene detecting via hybridization or sequencing, making it impossible to identify the cellular origin of individual nucleic acids.